which enables changing FileDialogHelper over to welded

Change-Id: I988342a6574cb7ed09b2724929e8c7117474a56c
Reviewed-on: https://gerrit.libreoffice.org/52388Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>